1
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Empting E, Bader N, Oettel M. Interplay of orientational order and roughness in simulated thin film growth of anisotropically interacting particles. Phys Rev E 2022; 105:045306. [PMID: 35590594 DOI: 10.1103/physreve.105.045306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 03/29/2022] [Indexed: 06/15/2023]
Abstract
Roughness and orientational order in thin films of anisotropic particles are investigated using kinetic Monte Carlo simulations on a cubic lattice. Anisotropic next-neighbor interactions between the lattice particles were chosen to mimic the effects of shape anisotropy in the interactions of disk- or rodlike molecules with van der Waals attractions. Increasing anisotropy leads first to a preferred orientation in the film (which is close to the corresponding equilibrium transition) while the qualitative mode of roughness evolution (known from isotropic systems) does not change. At strong anisotropies, an effective step-edge (Ehrlich-Schwoebel) barrier appears and a nonequilibrium roughening effect is found, accompanied by reordering in the film which can be interpreted as the nucleation and growth of domains of lying-down disks or rods. The information on order and roughness is combined into a diagram of dynamic growth modes.
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Affiliation(s)
- E Empting
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - N Bader
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - M Oettel
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
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2
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Duva G, Pithan L, Gerlach A, Janik A, Hinderhofer A, Schreiber F. Roughness evolution in strongly interacting donor:acceptor mixtures of molecular semiconductors. An in situ, real-time growth study using x-ray reflectivity. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:115003. [PMID: 33285533 DOI: 10.1088/1361-648x/abd11c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The evolution of surface roughness in binary mixtures of the two molecular organic semiconductors (OSCs) diindenoperylene (DIP) as electron-donor and 1, 3, 4, 5, 7, 8-hexafluoro-tetracyano naphthoquinodimethane (F6TCNNQ) as electron-acceptor is studied. We co-deposit DIP and F6TCNNQ in vacuum with varying relative molar content while keeping a molar excess of DIP in order to produce phase-heterogeneous mixtures. The excess DIP phase segregates in pristine crystallites, whereas the remaining mixed phase is constituted by DIP:F6TCNNQ co-crystallites. We calculate the surface roughness as function of film thickness by modelling x-ray reflectivity data acquired in situ and in real-time during film growth. To model the experimental data, two distinct approaches, namely the kinematic approximation and the Parratt formalism, are applied. A comparative study of surface roughness evolution as function of DIP:F6TCNNQ mixing ratio is carried out implementing the Trofimov growth model within the kinematic approximation. Depending on the thickness regime, mixing ratio-specific trends are identified and discussed. To explain them, a growth mechanism for binary heterogeneous mixtures of strongly interacting OSCs is proposed.
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Affiliation(s)
- G Duva
- University of Tübingen, Institute for Applied Physics, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - L Pithan
- ESRF - The European Synchrotron, 71, Avenue des Martyrs, 38000 Grenoble, France
| | - A Gerlach
- University of Tübingen, Institute for Applied Physics, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - A Janik
- University of Tübingen, Institute for Applied Physics, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - A Hinderhofer
- University of Tübingen, Institute for Applied Physics, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - F Schreiber
- University of Tübingen, Institute for Applied Physics, Auf der Morgenstelle 10, 72076 Tübingen, Germany
- Center for Light-Matter Interactions, Sensors and Analytics (LISA+), Auf der Morgenstelle 15, 72076 Tübingen, Germany
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3
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Hansmann AK, Döring RC, Rinn A, Giesen SM, Fey M, Breuer T, Berger R, Witte G, Chatterjee S. Charge Transfer Excitation and Asymmetric Energy Transfer at the Interface of Pentacene-Perfluoropentacene Heterostacks. ACS APPLIED MATERIALS & INTERFACES 2021; 13:5284-5292. [PMID: 33492144 DOI: 10.1021/acsami.0c16172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
High-performance solar cells demand efficient charge-carrier excitation, separation, and extraction. These requirements hold particularly true for molecular photovoltaics, where large exciton binding energies render charge separation challenging at their commonly complex donor-acceptor interface structure. Among others, charge-transfer (CT) states are considered to be important precursors for exciton dissociation and charge separation. However, the general nature of CT excitons and their formation pathways remain unclear. Layered quasiplanar crystalline molecular heterostructures of the prototypical donor-acceptor system pentacene-perfluoropentacene studied at cryogenic temperatures are a paramount model system to gain insights into the underlying physical mechanism. In particular, a detailed experiment-theory analysis on a layered heterojunction featuring perfluoropentacene in its π-stacked polymorph and pentacene in the Siegrist phase indicates that exciton diffusion in unitary films can influence the formation efficiency of CT excitons localized at internal interfaces for these conditions. The correlation of the structural characteristics, that is, the molecular arrangement at the interfaces, with their absorption and photoluminescence excitation spectra is consistent with exciton transfer from pentacene to the CT exciton state only, whereas no transfer of excitons from the perfluoropentacene is detected. Electronic structure calculations of the model systems and investigation of coupling matrix elements between the various electronic states involved suggest hampered exciton diffusion toward the internal interface in the perfluoropentacene films. The asymmetric energy landscape around an idealized internal donor-acceptor interface thus is identified as a reason for asymmetric energy transfer. Thus, long-range effects apparently can influence charge separation in crystalline molecular heterostructures, similar to band gap bowing, which is well established for inorganic pn-junctions.
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Affiliation(s)
- Anna-Katharina Hansmann
- Department of Chemistry, Philipps-University Marburg, Hans-Meerwein-Straße 4, Marburg D-35032, Germany
| | - Robin C Döring
- Institute of Experimental Physics I and Center for Materials Research (LaMa), Justus Liebig University Giessen, Heinrich-Buff-Ring 16, D-35392 Giessen, Germany
| | - Andre Rinn
- Institute of Experimental Physics I and Center for Materials Research (LaMa), Justus Liebig University Giessen, Heinrich-Buff-Ring 16, D-35392 Giessen, Germany
| | - Steffen M Giesen
- Department of Chemistry, Philipps-University Marburg, Hans-Meerwein-Straße 4, Marburg D-35032, Germany
| | - Melanie Fey
- Institute of Experimental Physics I and Center for Materials Research (LaMa), Justus Liebig University Giessen, Heinrich-Buff-Ring 16, D-35392 Giessen, Germany
| | - Tobias Breuer
- Department of Physics and Materials Sciences Center, Philipps-University Marburg, Renthof 7, Marburg D-35032, Germany
| | - Robert Berger
- Department of Chemistry, Philipps-University Marburg, Hans-Meerwein-Straße 4, Marburg D-35032, Germany
| | - Gregor Witte
- Department of Physics and Materials Sciences Center, Philipps-University Marburg, Renthof 7, Marburg D-35032, Germany
| | - Sangam Chatterjee
- Institute of Experimental Physics I and Center for Materials Research (LaMa), Justus Liebig University Giessen, Heinrich-Buff-Ring 16, D-35392 Giessen, Germany
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4
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Reisz B, Belova V, Duva G, Zeiser C, Hodas M, Hagara J, Šiffalovič P, Pithan L, Hosokai T, Hinderhofer A, Gerlach A, Schreiber F. Polymorphism and structure formation in copper phthalocyanine thin films. J Appl Crystallogr 2021; 54:203-210. [PMID: 33833648 PMCID: PMC7941321 DOI: 10.1107/s1600576720015472] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 11/22/2020] [Indexed: 11/30/2022] Open
Abstract
This X-ray diffraction study proves that two α polymorphs of copper pthalocyanine (CuPc) co-exist in vacuum-deposited thin films and provides possible molecular configurations by excluded-volume considerations. Furthermore, atomic force microscopy images together with a simple MATLAB simulation show that elevated substrate temperatures facilitate the downward diffusion of CuPc molecules during film growth and lead to a smoother surface. Many polymorphic crystal structures of copper phthalocyanine (CuPc) have been reported over the past few decades, but despite its manifold applicability, the structure of the frequently mentioned α polymorph remained unclear. The base-centered unit cell (space group C2/c) suggested in 1966 was ruled out in 2003 and was replaced by a primitive triclinic unit cell (space group P1). This study proves unequivocally that both α structures coexist in vacuum-deposited CuPc thin films on native silicon oxide by reciprocal space mapping using synchrotron radiation in grazing incidence. The unit-cell parameters and the space group were determined by kinematic scattering theory and provide possible molecular arrangements within the unit cell of the C2/c structure by excluded-volume considerations. In situ X-ray diffraction experiments and ex situ atomic force microscopy complement the experimental data further and provide insight into the formation of a smooth thin film by a temperature-driven downward diffusion of CuPc molecules during growth.
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Affiliation(s)
- Berthold Reisz
- Institute for Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Valentina Belova
- Institute for Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Giuliano Duva
- Institute for Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Clemens Zeiser
- Institute for Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Martin Hodas
- Institute for Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Jakub Hagara
- Institute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, 845 11 Bratislava 45, Slovak Republic
| | - Peter Šiffalovič
- Institute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, 845 11 Bratislava 45, Slovak Republic
| | - Linus Pithan
- European Synchrotron Radiation Facility, 71 avenue des Martyrs CS 402200, 38043 Grenoble Cedex 9, France
| | - Takuya Hosokai
- National Metrology Institute of Japan (NMIJ), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Azuma, Tsukuba, Ibaraki 305-8565, Japan
| | - Alexander Hinderhofer
- Institute for Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Alexander Gerlach
- Institute for Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Frank Schreiber
- Institute for Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
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5
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Hammer S, Zeiser C, Deutsch M, Engels B, Broch K, Pflaum J. Spatial Anisotropy of Charge Transfer at Perfluoropentacene-Pentacene (001) Single-Crystal Interfaces and its Relevance for Thin Film Devices. ACS APPLIED MATERIALS & INTERFACES 2020; 12:53547-53556. [PMID: 33167608 DOI: 10.1021/acsami.0c17152] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Archetypal donor-acceptor (D-A) interfaces composed of perfluoropentacene (PFP) and pentacene (PEN) are examined for charge transfer (CT) state formation and energetics as a function of their respective molecular configuration. To exclude morphological interference, our structural as well as highly sensitive differential reflectance spectroscopy studies were carried out on PFP thin films epitaxially grown on PEN(001) single-crystal facets. Whereas the experimental data supported by complementary theoretical calculations confirm the formation of a strong CT state in the case of a cofacial PFP-PEN stacking, CT formation is energetically less favorable and thus absent for the corresponding head-to-tail configuration as disclosed for the first time. In view of technological implementations, the knowledge gained on the single-crystal references is transferred to thin-film diodes composed of either stacked PFP/PEN bilayers or mixed PFP:PEN heterojunction interfaces. As demonstrated, their electronic and electroluminescent behavior can be consistently described by the absence or presence of interfacial CT states. Thus, our results hint at the thorough design of D-A interfaces to achieve the highest device performances.
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Affiliation(s)
- Sebastian Hammer
- Experimental Physics VI, Julius Maximilians University Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Clemens Zeiser
- Institute for Applied Physics, Eberhard Karls University Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Marian Deutsch
- Institute for Physical and Theoretical Chemistry, Julius Maximilians University Würzburg, Emil-Fischer-Straße 42, 97074 Würzburg, Germany
| | - Bernd Engels
- Institute for Physical and Theoretical Chemistry, Julius Maximilians University Würzburg, Emil-Fischer-Straße 42, 97074 Würzburg, Germany
| | - Katharina Broch
- Institute for Applied Physics, Eberhard Karls University Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Jens Pflaum
- Experimental Physics VI, Julius Maximilians University Würzburg, Am Hubland, 97074 Würzburg, Germany
- Bavarian Center for Applied Energy Research, Magdalene-Schoch-Straße 3, 97074 Würzburg, Germany
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6
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Zou T, Chang J, Chen Q, Nie Z, Duan L, Guo T, Song Y, Wu W, Wang H. Novel Strategy for Organic Cocrystals of n-Type and p-Type Organic Semiconductors with Advanced Optoelectronic Properties. ACS OMEGA 2020; 5:12067-12072. [PMID: 32548385 PMCID: PMC7271014 DOI: 10.1021/acsomega.0c00276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 04/30/2020] [Indexed: 05/13/2023]
Abstract
Cocrystallization has been applied widely for material synthesis. Recently cocrystal of organic molecules has been developing rapidly, taking the advantages of the flexibility and self-assembly of organic molecules. Here we report an experimental study of a cocrystal of copper-phthalocyanines and fluorinated ones. We have grown the samples via the vapor-phase deposition of the mixture with different mass ratios from 1:13.5 to 6:1. As suggested by our scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy, new crystal structures and morphologies through our novel strategy for the cocrystallization of these molecules have been found. Our work will provide a solid foundation to systematically synthesize the cocrystal of phthalocyanine molecules with new crystal structures, thus providing the opportunity to advance material properties.
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Affiliation(s)
- Taoyu Zou
- Key
Laboratory of Yunnan Provincial Higher Education Institutions for
Organic Optoelectronic Materials and Devices, Kunming University, Kunming 650214, People’s Republic
of China
- Kunming
DeepLand Nanomaterial Research Institute, Yunnan Ocean Organic Optoelectronic Technology Ltd, Kunming 650214, People’s Republic of China
| | - Jiawei Chang
- Key
Laboratory of Yunnan Provincial Higher Education Institutions for
Organic Optoelectronic Materials and Devices, Kunming University, Kunming 650214, People’s Republic
of China
| | - Qiuyuan Chen
- Key
Laboratory of Yunnan Provincial Higher Education Institutions for
Organic Optoelectronic Materials and Devices, Kunming University, Kunming 650214, People’s Republic
of China
| | - Zhifeng Nie
- Key
Laboratory of Yunnan Provincial Higher Education Institutions for
Organic Optoelectronic Materials and Devices, Kunming University, Kunming 650214, People’s Republic
of China
- Kunming
DeepLand Nanomaterial Research Institute, Yunnan Ocean Organic Optoelectronic Technology Ltd, Kunming 650214, People’s Republic of China
| | - Liangfei Duan
- Key
Laboratory of Yunnan Provincial Higher Education Institutions for
Organic Optoelectronic Materials and Devices, Kunming University, Kunming 650214, People’s Republic
of China
- Kunming
DeepLand Nanomaterial Research Institute, Yunnan Ocean Organic Optoelectronic Technology Ltd, Kunming 650214, People’s Republic of China
| | - Tingting Guo
- Key
Laboratory of Yunnan Provincial Higher Education Institutions for
Organic Optoelectronic Materials and Devices, Kunming University, Kunming 650214, People’s Republic
of China
- Kunming
DeepLand Nanomaterial Research Institute, Yunnan Ocean Organic Optoelectronic Technology Ltd, Kunming 650214, People’s Republic of China
| | - Yumin Song
- Key
Laboratory of Yunnan Provincial Higher Education Institutions for
Organic Optoelectronic Materials and Devices, Kunming University, Kunming 650214, People’s Republic
of China
- Kunming
DeepLand Nanomaterial Research Institute, Yunnan Ocean Organic Optoelectronic Technology Ltd, Kunming 650214, People’s Republic of China
| | - Wei Wu
- UCL
Department of Physics and Astronomy and London Centre for Nanotechnology, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Hai Wang
- Key
Laboratory of Yunnan Provincial Higher Education Institutions for
Organic Optoelectronic Materials and Devices, Kunming University, Kunming 650214, People’s Republic
of China
- Kunming
DeepLand Nanomaterial Research Institute, Yunnan Ocean Organic Optoelectronic Technology Ltd, Kunming 650214, People’s Republic of China
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7
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Wang Q, Franco-Cañellas A, Yang J, Hausch J, Struzek S, Chen M, Thakur PK, Gerlach A, Duhm S, Schreiber F. Heteromolecular Bilayers on a Weakly Interacting Substrate: Physisorptive Bonding and Molecular Distortions of Copper-Hexadecafluorophthalocyanine. ACS APPLIED MATERIALS & INTERFACES 2020; 12:14542-14551. [PMID: 32109044 DOI: 10.1021/acsami.9b22812] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Heteromolecular bilayers of π-conjugated organic molecules on metals, considered as model systems for more complex thin film heterostructures, are investigated with respect to their structural and electronic properties. By exploring the influence of the organic-metal interaction strength in bilayer systems, we determine the molecular arrangement in the physisorptive regime for copper-hexadecafluorophthalocyanine (F16CuPc) on Au(111) with intermediate layers of 5,7,12,14-pentacenetetrone and perylene-3,4,9,10-tetracarboxylic diimide. Using the X-ray standing wave technique to distinguish the different molecular layers, we show that these two bilayers are ordered following their deposition sequence. Surprisingly, F16CuPc as the second layer within the heterostructures exhibits an inverted intramolecular distortion compared to its monolayer structure.
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Affiliation(s)
- Qi Wang
- Institut für Angewandte Physik, Universität Tübingen, 72076 Tübingen, Germany
| | | | - Jiacheng Yang
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices and Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123, People's Republic of China
| | - Julian Hausch
- Institut für Angewandte Physik, Universität Tübingen, 72076 Tübingen, Germany
| | - Samuel Struzek
- Institut für Angewandte Physik, Universität Tübingen, 72076 Tübingen, Germany
| | - Mengting Chen
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices and Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123, People's Republic of China
| | - Pardeep Kumar Thakur
- Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE, United Kingdom
| | - Alexander Gerlach
- Institut für Angewandte Physik, Universität Tübingen, 72076 Tübingen, Germany
| | - Steffen Duhm
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices and Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123, People's Republic of China
| | - Frank Schreiber
- Institut für Angewandte Physik, Universität Tübingen, 72076 Tübingen, Germany
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8
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Schweicher G, Garbay G, Jouclas R, Vibert F, Devaux F, Geerts YH. Molecular Semiconductors for Logic Operations: Dead-End or Bright Future? ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1905909. [PMID: 31965662 DOI: 10.1002/adma.201905909] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 11/18/2019] [Indexed: 05/26/2023]
Abstract
The field of organic electronics has been prolific in the last couple of years, leading to the design and synthesis of several molecular semiconductors presenting a mobility in excess of 10 cm2 V-1 s-1 . However, it is also started to recently falter, as a result of doubtful mobility extractions and reduced industrial interest. This critical review addresses the community of chemists and materials scientists to share with it a critical analysis of the best performing molecular semiconductors and of the inherent charge transport physics that takes place in them. The goal is to inspire chemists and materials scientists and to give them hope that the field of molecular semiconductors for logic operations is not engaged into a dead end. To the contrary, it offers plenty of research opportunities in materials chemistry.
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Affiliation(s)
- Guillaume Schweicher
- Laboratoire de chimie des polymères, Faculté des Sciences, Université Libre de Bruxelles (ULB) Boulevard du Triomphe, Brussels, 1050, Belgium
- Optoelectronics Group, Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Guillaume Garbay
- Laboratoire de chimie des polymères, Faculté des Sciences, Université Libre de Bruxelles (ULB) Boulevard du Triomphe, Brussels, 1050, Belgium
| | - Rémy Jouclas
- Laboratoire de chimie des polymères, Faculté des Sciences, Université Libre de Bruxelles (ULB) Boulevard du Triomphe, Brussels, 1050, Belgium
| | - François Vibert
- Laboratoire de chimie des polymères, Faculté des Sciences, Université Libre de Bruxelles (ULB) Boulevard du Triomphe, Brussels, 1050, Belgium
| | - Félix Devaux
- Laboratoire de chimie des polymères, Faculté des Sciences, Université Libre de Bruxelles (ULB) Boulevard du Triomphe, Brussels, 1050, Belgium
| | - Yves H Geerts
- Laboratoire de chimie des polymères, Faculté des Sciences, Université Libre de Bruxelles (ULB) Boulevard du Triomphe, Brussels, 1050, Belgium
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9
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Kim VO, Broch K, Belova V, Chen YS, Gerlach A, Schreiber F, Tamura H, Della Valle RG, D'Avino G, Salzmann I, Beljonne D, Rao A, Friend R. Singlet exciton fission via an intermolecular charge transfer state in coevaporated pentacene-perfluoropentacene thin films. J Chem Phys 2019; 151:164706. [PMID: 31675857 DOI: 10.1063/1.5130400] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Singlet exciton fission is a spin-allowed process in organic semiconductors by which one absorbed photon generates two triplet excitons. Theory predicts that singlet fission is mediated by intermolecular charge-transfer states in solid-state materials with appropriate singlet-triplet energy spacing, but direct evidence for the involvement of such states in the process has not been provided yet. Here, we report on the observation of subpicosecond singlet fission in mixed films of pentacene and perfluoropentacene. By combining transient spectroscopy measurements to nonadiabatic quantum-dynamics simulations, we show that direct excitation in the charge-transfer absorption band of the mixed films leads to the formation of triplet excitons, unambiguously proving that they act as intermediate states in the fission process.
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Affiliation(s)
- Vincent O Kim
- Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge CB3 0HE, United Kingdom
| | - Katharina Broch
- Fritz Haber Institute of the Max Planck Society, Department of Physical Chemistry, Faradayweg, 4-614195 Berlin, Germany
| | - Valentina Belova
- Eberhard-Karls Universität Tübingen, Institut für Angewandte Physik, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Y S Chen
- Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge CB3 0HE, United Kingdom
| | - Alexander Gerlach
- Eberhard-Karls Universität Tübingen, Institut für Angewandte Physik, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Frank Schreiber
- Eberhard-Karls Universität Tübingen, Institut für Angewandte Physik, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Hiroyuki Tamura
- Department of Chemical System Engineering, The University of Tokyo, Tokyo 113-8656, Japan
| | - Raffaele Guido Della Valle
- Dipartimento di Chimica Industriale "Toso Montanari", Università di Bologna and INSTM-UdR Bologna, Viale Risorgimento 4, 40136 Bologna, Italy
| | - Gabriele D'Avino
- Institut Néel, CNRS and Grenoble Alpes University, F-38042 Grenoble, France
| | - Ingo Salzmann
- Department of Physics, Department of Chemistry and Biochemistry, Centre for Research in Molecular Modeling (CERMM), Centre for NanoScience Research (CeNSR), Concordia University, 7141 Sherbrooke St. West, Montreal, Quebec H4B 1R6, Canada
| | - David Beljonne
- Laboratory for Chemistry of Novel Materials, Department of Chemistry, Université de Mons, Place du Parc 20, 7000 Mons, Belgium
| | - Akshay Rao
- Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge CB3 0HE, United Kingdom
| | - Richard Friend
- Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge CB3 0HE, United Kingdom
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10
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Duva G, Beyer P, Scholz R, Belova V, Opitz A, Hinderhofer A, Gerlach A, Schreiber F. Ground-state charge-transfer interactions in donor:acceptor pairs of organic semiconductors - a spectroscopic study of two representative systems. Phys Chem Chem Phys 2019; 21:17190-17199. [PMID: 31364636 DOI: 10.1039/c9cp02939g] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
We investigate blended donor:acceptor (D:A) thin films of the two donors diindenoperylene (DIP) and poly(3-hexylthiophene) (P3HT) mixed with the strong acceptor 1,3,4,5,7,8-hexafluorotetracyanonaphthoquinodimethane (F6TCNNQ) using Polarization-Modulation Infrared Reflection-Absorption Spectroscopy (PMIRRAS). For DIP:F6TCNNQ thin films we first carry out a comprehensive study of the structure as a function of the D : A mixing ratio, which guides the analysis of the PMIRRAS spectra. In particular, from the red-shift of the nitrile (C[triple bond, length as m-dash]N) stretching of F6TCNNQ in the different mixtures with DIP, we quantify the average ground-state charge-transfer (GS-CT) to be ρavg = (0.84 ± 0.04) e. The PMIRRAS data for P3HT:F6TCNNQ blended films reveal nearly the same shift of the CT-affected C[triple bond, length as m-dash]N stretching peak for this system. This points towards a very similar CT strength for the two systems. We extend the analysis to the relative intensity of the C[triple bond, length as m-dash]N to the C[double bond, length as m-dash]C stretching modes of F6TCNNQ in the mixtures with DIP and P3HT, respectively, and support it with DFT calculations for the isolated F6TCNNQ. Such comparison allows to identify the vibrational signatures of the acceptor mono-anion in P3HT:F6TCNNQ, thus indicating a much stronger, integer CT-type interactions for this system, in agreement with available optical spectroscopy data. Our findings stress the importance of a simultaneous analysis of C[triple bond, length as m-dash]N and C[double bond, length as m-dash]C stretching vibrations in F6TCNNQ, or similar quinoid systems, for a reliable picture of the nature of GS-CT interactions.
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Affiliation(s)
- Giuliano Duva
- University of Tübingen, Institute for Applied Physics, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
| | - Paul Beyer
- Humboldt-Universität zu Berlin, Department of Physics, Newtonstraße 15, 12489 Berlin, Germany
| | - Reinhard Scholz
- Dresden Integrated Center for Applied Physics and Photonic Materials, Nöthnitzer Str. 61, 01187 Dresden, Germany
| | - Valentina Belova
- University of Tübingen, Institute for Applied Physics, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
| | - Andreas Opitz
- Humboldt-Universität zu Berlin, Department of Physics, Newtonstraße 15, 12489 Berlin, Germany
| | - Alexander Hinderhofer
- University of Tübingen, Institute for Applied Physics, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
| | - Alexander Gerlach
- University of Tübingen, Institute for Applied Physics, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
| | - Frank Schreiber
- University of Tübingen, Institute for Applied Physics, Auf der Morgenstelle 10, 72076 Tübingen, Germany. and Center for Light-Matter Interactions, Sensors & Analytics (LISA+), Auf der Morgenstelle 15, 72076 Tübingen, Germany
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11
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Rinn A, Breuer T, Wiegand J, Beck M, Hübner J, Döring RC, Oestreich M, Heimbrodt W, Witte G, Chatterjee S. Interfacial Molecular Packing Determines Exciton Dynamics in Molecular Heterostructures: The Case of Pentacene-Perfluoropentacene. ACS APPLIED MATERIALS & INTERFACES 2017; 9:42020-42028. [PMID: 29135216 DOI: 10.1021/acsami.7b11118] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The great majority of electronic and optoelectronic devices depend on interfaces between p-type and n-type semiconductors. Finding matching donor-acceptor systems in molecular semiconductors remains a challenging endeavor because structurally compatible molecules may not necessarily be suitable with respect to their optical and electronic properties, and the large exciton binding energy in these materials may favor bound electron-hole pairs rather than free carriers or charge transfer at an interface. Regardless, interfacial charge-transfer exciton states are commonly considered as an intermediate step to achieve exciton dissociation. The formation efficiency and decay dynamics of such states will strongly depend on the molecular makeup of the interface, especially the relative alignment of donor and acceptor molecules. Structurally well-defined pentacene-perfluoropentacene heterostructures of different molecular orientations are virtually ideal model systems to study the interrelation between molecular packing motifs at the interface and their electronic properties. Comparing the emission dynamics of the heterosystems and the corresponding unitary films enables accurate assignment of every observable emission signal in the heterosystems. These heterosystems feature two characteristic interface-specific luminescence channels at around 1.4 and 1.5 eV that are not observed in the unitary samples. Their emission strength strongly depends on the molecular alignment of the respective donor and acceptor molecules, emphasizing the importance of structural control for device construction.
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Affiliation(s)
- Andre Rinn
- Faculty of Physics & Materials Sciences Centre, Philipps-Universität Marburg , Renthof 5, 35032 Marburg, Germany
| | - Tobias Breuer
- Faculty of Physics & Materials Sciences Centre, Philipps-Universität Marburg , Renthof 5, 35032 Marburg, Germany
| | - Julia Wiegand
- Institut für Festkörperphysik, Leibniz Universität Hannover , Appelstrasse 2, D-30167 Hannover, Germany
| | - Michael Beck
- Institut für Festkörperphysik, Leibniz Universität Hannover , Appelstrasse 2, D-30167 Hannover, Germany
| | - Jens Hübner
- Institut für Festkörperphysik, Leibniz Universität Hannover , Appelstrasse 2, D-30167 Hannover, Germany
| | - Robin C Döring
- Faculty of Physics & Materials Sciences Centre, Philipps-Universität Marburg , Renthof 5, 35032 Marburg, Germany
| | - Michael Oestreich
- Institut für Festkörperphysik, Leibniz Universität Hannover , Appelstrasse 2, D-30167 Hannover, Germany
| | - Wolfram Heimbrodt
- Faculty of Physics & Materials Sciences Centre, Philipps-Universität Marburg , Renthof 5, 35032 Marburg, Germany
| | - Gregor Witte
- Faculty of Physics & Materials Sciences Centre, Philipps-Universität Marburg , Renthof 5, 35032 Marburg, Germany
| | - Sangam Chatterjee
- Faculty of Physics & Materials Sciences Centre, Philipps-Universität Marburg , Renthof 5, 35032 Marburg, Germany
- Institute of Experimental Physics I, Justus-Liebig-University Giessen , Heinrich-Buff-Ring 16, D-35392 Giessen, Germany
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12
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Belova V, Beyer P, Meister E, Linderl T, Halbich MU, Gerhard M, Schmidt S, Zechel T, Meisel T, Generalov AV, Anselmo AS, Scholz R, Konovalov O, Gerlach A, Koch M, Hinderhofer A, Opitz A, Brütting W, Schreiber F. Evidence for Anisotropic Electronic Coupling of Charge Transfer States in Weakly Interacting Organic Semiconductor Mixtures. J Am Chem Soc 2017; 139:8474-8486. [PMID: 28570061 DOI: 10.1021/jacs.7b01622] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We present a comprehensive investigation of the charge-transfer (CT) effect in weakly interacting organic semiconductor mixtures. The donor-acceptor pair diindenoperylene (DIP) and N,N'-bis(2-ethylhexyl)-1,7-dicyanoperylene-3,4/9,10-bis(dicarboxyimide) (PDIR-CN2) has been chosen as a model system. A wide range of experimental methods was used in order to characterize the structural, optical, electronic, and device properties of the intermolecular interactions. By detailed analysis, we demonstrate that the partial CT in this weakly interacting mixture does not have a strong effect on the ground state and does not generate a hybrid orbital. We also find a strong CT transition in light absorption as well as in photo- and electroluminescence. By using different layer sequences and compositions, we are able to distinguish electronic coupling in-plane vs out-of-plane and, thus, characterize the anisotropy of the CT state. Finally, we discuss the impact of CT exciton generation on charge-carrier transport and on the efficiency of photovoltaic devices.
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Affiliation(s)
- Valentina Belova
- Institut für Angewandte Physik, Universität Tübingen , Tübingen 72076, Germany
| | - Paul Beyer
- Department of Physics, Humboldt-Universität zu Berlin , Berlin 10099, Germany
| | - Eduard Meister
- Institute of Physics, Experimental Physics IV, University of Augsburg , Augsburg 86135, Germany
| | - Theresa Linderl
- Institute of Physics, Experimental Physics IV, University of Augsburg , Augsburg 86135, Germany
| | - Marc-Uwe Halbich
- Faculty of Physics and Material Sciences Center, Philipps-Universität Marburg , Marburg 35037, Germany
| | - Marina Gerhard
- Faculty of Physics and Material Sciences Center, Philipps-Universität Marburg , Marburg 35037, Germany
| | - Stefan Schmidt
- Institute of Physics, Experimental Physics IV, University of Augsburg , Augsburg 86135, Germany
| | - Thomas Zechel
- Institute of Physics, Experimental Physics IV, University of Augsburg , Augsburg 86135, Germany
| | - Tino Meisel
- Department of Physics, Humboldt-Universität zu Berlin , Berlin 10099, Germany
| | | | - Ana Sofia Anselmo
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , Berlin 14109, Germany
| | - Reinhard Scholz
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP), Technische Universität Dresden , Dresden 01062, Germany
| | - Oleg Konovalov
- European Synchrotron Radiation Facility, Grenoble 38000, France
| | - Alexander Gerlach
- Institut für Angewandte Physik, Universität Tübingen , Tübingen 72076, Germany
| | - Martin Koch
- Faculty of Physics and Material Sciences Center, Philipps-Universität Marburg , Marburg 35037, Germany
| | | | - Andreas Opitz
- Department of Physics, Humboldt-Universität zu Berlin , Berlin 10099, Germany
| | - Wolfgang Brütting
- Institute of Physics, Experimental Physics IV, University of Augsburg , Augsburg 86135, Germany
| | - Frank Schreiber
- Institut für Angewandte Physik, Universität Tübingen , Tübingen 72076, Germany
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13
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Breuer T, Witte G. Controlling Nanostructures by Templated Templates: Inheriting Molecular Orientation in Binary Heterostructures. ACS APPLIED MATERIALS & INTERFACES 2015; 7:20485-20492. [PMID: 26305339 DOI: 10.1021/acsami.5b07409] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Precise preparation strategies are required to fabricate molecular nanostructures of specific arrangement. In bottom-up approaches, where nanostructures are gradually formed by piecing together individual parts to the final structure, the self-ordering mechanisms of the involved structures are utilized. In order to achieve the desired structures regarding morphology, grain size, and orientation of the individual moieties, templates can be applied, which influence the formation process of subsequent structures. However, this strategy is of limited use for complex architectures because the templates only influence the structure formation at the interface between the template and the first compound. Here, we discuss the implementation of so-called templated templates and analyze to what extent orientations of the initial layers are inherited in the top layers of another compound to enable structural control in binary heterostructures. For that purpose, we prepared crystalline templates of the organic semiconductors pentacene and perfluoropentacene in different exclusive orientations. We observe that for templates of both individual materials the molecular orientation is inherited in the top layers of the respective counterpart. This behavior is also observed for various other molecules, indicating the robustness of this approach.
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Affiliation(s)
- Tobias Breuer
- Fachbereich Physik, Philipps-Universität Marburg , 35032 Marburg, Germany
| | - Gregor Witte
- Fachbereich Physik, Philipps-Universität Marburg , 35032 Marburg, Germany
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14
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Broch K, Gerlach A, Lorch C, Dieterle J, Novák J, Hinderhofer A, Schreiber F. Structure formation in perfluoropentacene:diindenoperylene blends and its impact on transient effects in the optical properties studied in real-time during growth. J Chem Phys 2013; 139:174709. [PMID: 24206324 DOI: 10.1063/1.4827868] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- K Broch
- Universität Tübingen, Institut für Angewandte Physik and LISA+, Auf der Morgenstelle 10, 72076 Tübingen, Germany
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15
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Breuer T, Witte G. Diffusion-controlled growth of molecular heterostructures: fabrication of two-, one-, and zero-dimensional C(60) nanostructures on pentacene substrates. ACS APPLIED MATERIALS & INTERFACES 2013; 5:9740-9745. [PMID: 24004066 DOI: 10.1021/am402868s] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A variety of low dimensional C60 structures has been grown on supporting pentacene multilayers. By choice of substrate temperature during growth the effective diffusion length of evaporated fullerenes and their nucleation at terraces or step edges can be precisely controlled. AFM and SEM measurements show that this enables the fabrication of either 2D adlayers or solely 1D chains decorating substrate steps, while at elevated growth temperature continuous wetting of step edges is prohibited and instead the formation of separated C60 clusters pinned at the pentacene step edges occurs. Remarkably, all structures remain thermally stable at room temperature once they are formed. In addition the various fullerene structures have been overgrown by an additional pentacene capping layer. Utilizing the different probe depth of XRD and NEXAFS, we found that no contiguous pentacene film is formed on the 2D C60 structure, whereas an encapsulation of the 1D and 0D structures with uniformly upright oriented pentacene is achieved, hence allowing the fabrication of low dimensional buried organic heterostructures.
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Affiliation(s)
- Tobias Breuer
- Molekulare Festkörperphysik, Philipps-Universität Marburg , D-35032 Marburg, Germany
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16
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Breuer T, Witte G. Thermally activated intermixture in pentacene-perfluoropentacene heterostructures. J Chem Phys 2013; 138:114901. [DOI: 10.1063/1.4795004] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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17
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Aufderheide A, Broch K, Novák J, Hinderhofer A, Nervo R, Gerlach A, Banerjee R, Schreiber F. Mixing-induced anisotropic correlations in molecular crystalline systems. PHYSICAL REVIEW LETTERS 2012; 109:156102. [PMID: 23102338 DOI: 10.1103/physrevlett.109.156102] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Indexed: 06/01/2023]
Abstract
We investigate the structure of mixed thin films composed of pentacene and diindenoperylene using x-ray reflectivity and grazing incidence x-ray diffraction. For equimolar mixtures we observe vanishing in-plane order coexisting with an excellent out-of-plane order, a yet unreported disordering behavior in binary mixtures of organic semiconductors, which are crystalline in their pure form. One approach to rationalize our findings is to introduce an anisotropic interaction parameter in the framework of a mean field model. By comparing the structural properties with those of other mixed systems, we discuss the effects of sterical compatibility and chemical composition on the mixing behavior, which adds to the general understanding of interactions in molecular mixtures.
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Affiliation(s)
- A Aufderheide
- Universität Tübingen, Insitut für Angewandte Physik, Tübingen, Germany
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18
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Anger F, Ossó JO, Heinemeyer U, Broch K, Scholz R, Gerlach A, Schreiber F. Photoluminescence spectroscopy of pure pentacene, perfluoropentacene, and mixed thin films. J Chem Phys 2012; 136:054701. [DOI: 10.1063/1.3677839] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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19
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Hinderhofer A, Schreiber F. Organic-Organic Heterostructures: Concepts and Applications. Chemphyschem 2012; 13:628-43. [DOI: 10.1002/cphc.201100737] [Citation(s) in RCA: 125] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Indexed: 11/06/2022]
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20
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Djuric T, Hernandez-Sosa G, Schwabegger G, Koini M, Hesser G, Arndt M, Brinkmann M, Sitter H, Simbrunner C, Resel R. Alternately deposited heterostructures of α-sexithiophene–para-hexaphenyl on muscovite mica(001) surfaces: crystallographic structure and morphology. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm32023a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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